Cómo expandir AppBarLayout al desplazarse hacia abajo alcanza en la parte superior de la RecyclerView

Estoy trabajando en una aplicación android en la que estoy usando CoordinatorLayout , AppBarLayout y CollapsingToolbarLayout para usar la funcionalidad avanzada de barra de contracción.

Estoy usando recyclerview para mostrar el número de elementos en el fragmento. Cuando estoy desplazando hacia arriba recyclerview suavemente colapso AppBarLayout pero cuando me desplácese hacia abajo y llegar a en el primer elemento de la recyclerview automáticamente detener el desplazamiento sin la expansión de `AppBarLayout '.

• Vista fija en el diseño de contenido de Viewpager, bajo CoordinatorLayout
• AppBarLayout extrañamente toma espacio y empuja el contenido hacia abajo
• La barra de herramientas no se despliega incluso después de proporcionar el indicador "app: layout_scrollFlags"
• Cómo mostrar los elementos colapsados ​​en CoordinatorLayout mediante programación?
• ¿Cómo mostrar el logotipo de la barra de herramientas, icono, título, subtítulo cuando se envuelve en un CollapsingToolbarLayout?

Entonces otra vez necesito enrollar abajo otra vez para hacer AppBarLayout visible. Así que mi requisito es que al desplazarse hacia abajo cuando llego a la parte superior de recyclerview debe expandir `AppBarLayout '.

Cómo podemos hacer esto. Alguna idea ? Consulta el video de la misma https://www.dropbox.com/s/va5jk27ikytk5ax/app_collapsebar_issue.mp4?dl=0

Aquí está mi diseño de la misma: –

 <?xml version="1.0" encoding="utf-8"?> <android.support.v4.widget.DrawerLayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:app="http://schemas.android.com/apk/res-auto" android:id="@+id/drawerLayout" android:layout_width="match_parent" android:layout_height="match_parent" android:fitsSystemWindows="true"> <FrameLayout android:layout_width="match_parent" android:layout_height="match_parent"> <android.support.design.widget.CoordinatorLayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:app="http://schemas.android.com/apk/res-auto" xmlns:tools="http://schemas.android.com/tools" android:id="@+id/coordinator" android:layout_width="match_parent" android:layout_height="match_parent" android:adjustViewBounds="true" android:fitsSystemWindows="true" app:layout_scrollFlags="scroll|exitUntilCollapsed" > <android.support.design.widget.AppBarLayout android:id="@+id/app_bar" android:layout_width="match_parent" android:layout_height="220dp" android:background="@drawable/offer_image" android:fitsSystemWindows="true" android:theme="@style/AppTheme.AppBarOverlay" app:layout_scrollFlags="scroll|exitUntilCollapsed"> <!-- <com.flaviofaria.kenburnsview.KenBurnsView android:id="@+id/image" android:layout_width="match_parent" android:layout_height="220dp" android:src="@drawable/offer_image" />--> <android.support.design.widget.CollapsingToolbarLayout android:id="@+id/toolbar_layout" android:layout_width="match_parent" android:layout_height="match_parent" android:fitsSystemWindows="true" app:expandedTitleMarginEnd="64dp" app:expandedTitleMarginStart="48dp" app:layout_scrollFlags="scroll|exitUntilCollapsed"> <com.flaviofaria.kenburnsview.KenBurnsView android:id="@+id/image" android:layout_width="match_parent" android:layout_height="220dp" android:src="@drawable/offer_image" /> <FrameLayout android:id="@+id/collapse_frame" android:layout_width="match_parent" android:layout_height="match_parent" android:background="#B3c85a00"> </FrameLayout> <FrameLayout android:id="@+id/centerCircle" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_gravity="center"> <ImageView android:id="@+id/imageViewCenter" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_gravity="center" android:src="@drawable/offer" /> </FrameLayout> <include android:id="@+id/toolbar" layout="@layout/toolbar" /> <android.support.design.widget.TabLayout android:id="@+id/tabs" android:layout_width="match_parent" android:layout_height="wrap_content" android:layout_gravity="bottom" android:layout_marginBottom="15dp" app:tabIndicatorColor="#FFFFFF" app:tabMode="scrollable" /> <!--</FrameLayout>--> </android.support.design.widget.CollapsingToolbarLayout> </android.support.design.widget.AppBarLayout> <!--<FrameLayout--> <!--android:layout_width="match_parent"--> <!--android:layout_height="match_parent"--> <!-- --> <!--android:visibility="visible">--> <android.support.design.widget.FloatingActionButton android:id="@+id/fab" style="@style/floating_action_button" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_gravity="bottom|end" android:src="@drawable/ic_share_white_24dp" android:visibility="gone" app:backgroundTint="#FF9800" app:elevation="6dp" app:pressedTranslationZ="12dp" /> <android.support.v4.view.ViewPager xmlns:android="http://schemas.android.com/apk/res/android" android:id="@+id/pager" android:layout_width="match_parent" android:layout_height="wrap_content" android:layout_gravity="left|bottom|fill_vertical" android:layout_marginTop="0dp" app:layout_behavior="@string/appbar_scrolling_view_behavior"></android.support.v4.view.ViewPager> <!--</FrameLayout>--> <!--<include layout="@layout/content_scrolling" />--> </android.support.design.widget.CoordinatorLayout> <RelativeLayout android:id="@+id/bannerView" android:layout_width="match_parent" android:layout_height="58dp" android:layout_gravity="bottom|center" android:background="@drawable/curved_white_with_blue_border" android:visibility="gone"> <TextView android:id="@+id/bannerText" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_centerHorizontal="true" android:layout_centerInParent="true" android:layout_centerVertical="true" android:gravity="center" android:padding="3dp" android:text="Banner" android:visibility="gone" /> <ImageView android:id="@+id/bannerImage" android:layout_width="match_parent" android:layout_height="match_parent" android:layout_alignParentLeft="true" android:layout_centerHorizontal="true" android:layout_centerVertical="true" android:gravity="center" android:padding="3dp" android:scaleType="fitXY" android:visibility="gone" /> <ImageView android:id="@+id/bannerClose" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_alignParentRight="true" android:layout_alignParentTop="true" android:layout_centerVertical="true" android:src="@drawable/cross_icon" /> </RelativeLayout> <LinearLayout android:id="@+id/socialTabs" android:layout_width="match_parent" android:layout_height="46dp" android:layout_gravity="bottom|center" android:layout_marginBottom="5dp" android:background="@color/White" android:orientation="horizontal" android:visibility="gone"> <ImageView android:layout_width="wrap_content" android:layout_height="match_parent" android:adjustViewBounds="true" android:src="@drawable/follow" /> <FrameLayout android:layout_width="match_parent" android:layout_height="match_parent" android:layout_gravity="center" android:background="@color/White"> <LinearLayout android:layout_width="match_parent" android:layout_height="46dp" android:layout_gravity="center" android:gravity="center" android:paddingLeft="10dp" android:paddingRight="10dp" android:weightSum="3"> <ImageView android:id="@+id/facebookImageView" android:layout_width="30dp" android:layout_height="30dp" android:layout_weight="1" android:src="@drawable/fb_follow" /> <ImageView android:id="@+id/googlePlusImageView" android:layout_width="30dp" android:layout_height="30dp" android:layout_marginLeft="5dp" android:layout_marginRight="5dp" android:layout_weight="1" android:adjustViewBounds="true" android:src="@drawable/google_follow" /> <ImageView android:id="@+id/twitterImageView" android:layout_width="30dp" android:layout_height="30dp" android:layout_weight="1" android:adjustViewBounds="true" android:src="@drawable/twitter_follow" /> </LinearLayout> </FrameLayout> </LinearLayout> </FrameLayout> <ExpandableListView android:id="@+id/left_drawer" android:layout_width="265dp" android:layout_height="match_parent" android:layout_gravity="start" android:background="#fff" android:choiceMode="singleChoice" android:divider="@null" android:dividerHeight="0dp" android:drawSelectorOnTop="true" android:groupIndicator="@null" android:scrollbars="@null" /> </android.support.v4.widget.DrawerLayout> 

 public class ScrollFeedbackRecyclerView extends RecyclerView { private WeakReference<Callbacks> mCallbacks; public ScrollFeedbackRecyclerView(Context context) { super(context); attachCallbacks(context); } public ScrollFeedbackRecyclerView(Context context, AttributeSet attrs) { super(context, attrs); attachCallbacks(context); } /*If the first completely visible item in the RecyclerView is at index 0, then we're at the top of the list, so we want the AppBar to expand **if the AppBar is also collapsed** (otherwise the AppBar will constantly attempt to expand). */ @Override public void onScrolled(int dx, int dy) { if(((LinearLayoutManager)getLayoutManager()).findFirstCompletelyVisibleItemPosition() == 0) { Log.e(getClass().getSimpleName(), "index 0 visible"); if(mCallbacks.get().isAppBarCollapsed()) { mCallbacks.get().setExpanded(true); } } super.onScrolled(dx, dy); } /* the findFirstCompletelyVisibleItem() method is only available with LinearLayoutManager and its subclasses, so test for it when setting the LayoutManager */ @Override public void setLayoutManager(LayoutManager layout) { if(!(layout instanceof LinearLayoutManager)) { throw new IllegalArgumentException(layout.toString() + " must be of type LinearLayoutManager"); } super.setLayoutManager(layout); } private void attachCallbacks(Context context) { try { mCallbacks = new WeakReference<>((Callbacks)context); } catch (ClassCastException e) { throw new ClassCastException(context.toString() + " must implement " + "ScrollFeedbackRecyclerView.Callbacks"); } } /* Necessary to interact with the AppBarLayout in the hosting Activity */ interface Callbacks { boolean isAppBarCollapsed(); void setExpanded(boolean expanded); } } 

 public class MainActivity extends AppCompatActivity implements ScrollFeedbackRecyclerView.Callbacks{ private AppBarLayout mAppBarLayout; private Toolbar mToolbar; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); ScrollFeedbackRecyclerView mRecyclerView = (ScrollFeedbackRecyclerView) findViewById(R.id.rv_container); RecyclerViewAdapter mAdapter = new RecyclerViewAdapter(); mRecyclerView.setAdapter(mAdapter); mRecyclerView.setLayoutManager(new LinearLayoutManager(this)); mAppBarLayout = (AppBarLayout) findViewById(R.id.app_bar); mToolbar = (Toolbar) findViewById(R.id.toolbar); } /* When collapsed, calling getY() on the AppBar will return a negative number. Adding this number to getHeight() will return the same value as the toolbar's height if the AppBar is fully collapsed. */ @Override public boolean isAppBarCollapsed() { final int appBarVisibleHeight = (int) (mAppBarLayout.getY() + mAppBarLayout.getHeight()); final int toolbarHeight = mToolbar.getHeight(); return (appBarVisibleHeight == toolbarHeight); } @Override public void setExpanded(boolean expanded) { mAppBarLayout.setExpanded(expanded, true); } }